Electrodepositing bright polished coats of cadmium



Patented May 5, 1925. I

UNITED STATES 1,536,858 PATENT OFFICE.

CHAD .HEBBEBT HU'HPIIRIES, OF KOKOMO, INDIANA, ASSIGNOR T THE UDYLITE PROCESS comm, OF KOKOMO, INDIANA, -A CORPORATION OF INDIANA.

ELECTBODEPOSI'IING BRIGHT POLISHED COATS 0F CADMIUM.

'. Ho Drawing.

To all whom it may cimcem:

Be it known that I, CHAD H. HUMPHRIES,

a citizen of the United States, residing at Kokomo, in the countyofHoward and State of Indiana, have invented certain new and useful Improvements in Electrodepositing Bright Polished Coats. of Cadmium, of which the following is a specification.

This invention has for its object the elec- IlO trodeposition of a bright deposit of cadmium on another metal, such as steel or- In a prior application of Wissler and Humphries, Ser. No. 459,983 filed Apr. 9, 15 1921, is described a method of electrode- .positing cadmium from a cyanide solution. L The general features of the method therein described, viz, the use of insoluble anodes, a cyanide solution and a relatively high current density are used in carrying out the present process, but with certain modifications and additions which will now be described.

i It has been found that the use of addition agents very materially improves the character of the deposit, in that there is obtained a brighter, more dense cadmium surface, free from ores.

As an examp e of the method, a solution consisting of 1 gallon water; 0.415 pound sodium cyanide and 0.305 pound cadmium hydrate, is prepared to which is added a small amount of an addition agent, such as wool fibre. The quantity of wool used is solution. The effect of this addition is to produce a uniformly bright, dense, even deposit of cadmium. This effect is enhanced by agitation of the solution during the electrodeposition preferably by the use of compressed air.

It has been found that besides wool, there mium undercoat, be buffed up to a high from 0.025% to 0.01% of the weight of the 'tion in presence of an addition agent in Application filed March 2, 1922. Serial No. 540,566.

of about ampere per square inch or a littleless. The bath is preferably maintained at about 18 C. during the electrodeposition.

The solution above described contains 2.5% cadmium per litre, but this degree of concentration may be widely varied as from 1.25% to 5%.

Preferably the cadmium cyanide solution is kept neutral or basic.

The process above described produces a coating which is particularly adapted for use in several relations. Thus, the coated article may be used without further treatment, or we may subject it to a baking operation such as is described in the application above referred to, and in the Patent No. 1,383,174, to Udy and Nicholson.

The bright, dense, cadmium coating produced as above described has been found to be particularly advantageous, when nickel is electrodeposited on the cadmium coated article. It is found that the nickel coating can, without previous bufling of the cadfinish, and also that because of the dense poreless character of this cadmium undercoat, the double-coated article is particularly resistant to rust.

The nickel coating may be applied by well-known methods, but with a considerably shorter duration of plating time, there by lessening the cost of this step of the operation.

What is claimed is:

1. The method of obtaining a bright dense, coherent coating of metallic cadmium on another metal, which consists in electrodepositing cadmium from a cyanide soluquantity sufficient to produce an appreciable brightening effect but not exceeding 05%.

2. The method as claimed in claim 1, in which wool is used as the addition agent. 1

3. The method of obtaining a bright coherent dense coating of metallic cadmium on another metal which consists in electrodepositing cadmium from a cyanide solution in presence of an addition agent in quantity suflicient to produce an appreciable brightening efi'eot but not exceeding .05%, a graphite carbon or non-polarizing anode being used.

4. The method as claimed in claim 3, in 9 which wool is used as the addition agent.

5. The method of rust-proofing iron or steel articles which consists in electrodepositing thereon a bright, dense, coherent coating of metallic cadmium, and then electrodepositing nickel on the coated article to protect the cadmium coating against abrasion.

6. The method of protecting metals other than cadmium which consists in producing a bright, dense, coherent coating of memg nickel upon said coating of metallic cadmium to protect the same from abrasion.

7. The method of protecting metals other than cadmium which consists in producing a bright, dense, coherent coating of metallic cadmium thereon by electrodeposition from a cyanide solution in the presence of wool as an addition agent, and then electrodepositing nickel upon said coating of metallic cadmium to protect the same from abrasion.

8. As a new article of manufacture, a metal article having a bright, dense, coherent coating of metallic cadmium and an overlying protective coating of nickel.

In testimony whereof, I aifix my signature.

CHAD HERBERT HUMPHIRIES. 

